This invention relates to methods and arrangements for avoiding and/or minimizing vehicle collisions in road traffic.
The last few years have seen a rapid rise in the density of traffic on the roads, and in the flood of information available to a driver. Driving motor vehicles is thus becoming a complex procedure in which the vehicle driver can find himself in critical situations with which he is unable to cope.
For this reason, it is important to relieve the driver of a vehicle in particular in critical situations. So-called driver assistance systems are available to alert the driver of a vehicle to specific dangers. Thus, in order to define a degree of danger to which a vehicle is subjected because of dense traffic and low visibility, U.S. Pat. No. 5,410,304 describes an arrangement for sensing the spacing of a vehicle from the vehicle travelling ahead using distance-sensing devices, determining the relative speed between the two vehicles and/or between the vehicle and an obstacle using an infrared visibility measuring system, and detecting the current visibility and the instantaneous speed of the vehicle and its steering angle. In a first method step, a measure of a safe distance from a vehicle travelling in front and/or from an obstacle is established as a function of these variables, and an indication of an instantaneous vehicle speed, which can be increased or reduced if appropriate, is displayed. In a second method step, a vehicle speed which is still safe is calculated as a function of the measured visibility, and this speed value is compared with the safe distance speed value, the lower and/or the more negative of the two values being displayed in order to warn the driver of the vehicle. Such a driver assistance system, however, can only make an indirect contribution to the avoidance of accidents since it depends on the acceptance of the displayed information by the driver of the vehicle.
Furthermore, in the last few years, passive safety systems such as airbags and side impact protection systems have been incorporated into motor vehicles. These systems have in common the fact that they cannot be activated until an impact has taken place. Thus, such safety systems cannot prevent a collision from occurring but can only reduce its consequences for the occupants of the motor vehicle.
Furthermore, in the last few years, passive safety systems such as airbags and side impact protection systems have been incorporated into motor vehicles. These systems have in common the fact that they cannot be activated until an impact has taken place. Thus, such safety systems cannot prevent a collision from occurring but can only reduce its consequences for the occupants of the motor vehicle.
Furthermore, various seat-occupation detection devices are known by which it is possible to detect whether a vehicle seat is occupied. This information is required, for example, to determine whether or not a front seat passenger's airbag should be triggered in a collision. In addition, a seat-occupation detection device can also be used to sense the type of physiognomy of a person sitting on the vehicle seat by activating, for example, video cameras, weight sensors or the like. On the basis of the physiognomy which is sensed, the gas pressure of the airbag can then be appropriately controlled so that injuries resulting from the triggering of the airbag can be avoided.
It becomes possible to avoid an accident by using active safety systems such as an anti-lock braking system (ABS). However, the prerequisite for the response of an ABS is that the driver has detected the risk of an accident and initiates an appropriately high rate of deceleration. Thus, the successful use of active safety systems likewise depends directly on the driver of the vehicle. For this reason, methods and devices have been developed for preventing a collision with a vehicle travelling in front. These devices are capable, because of a certain degree of independence, of avoiding rear-end collisions.
As an example, the European Patent EP 545 437 describes a method for avoiding collisions of motor vehicles. In that method, the output signal of a distance-measuring device is supplied to an evaluation unit. The detection range of the distance-measuring device is divided into a series of safety zones which are at different distances from the vehicle and to which individual reaction measures are assigned. Such a reaction measure is primarily an indication of an imminent collision to the driver of a vehicle. If the driver of the vehicle does not react to this indication, appropriate action to reduce the risk of collision is automatically initiated. Vehicle-specific parameters such as speed and further factors which affect the acceleration characteristics such as the load of the motor vehicle and the condition of the roadway, as well as the visibility, are taken into account in the definition of the safety zones. However, such a system only reacts to a motor vehicle travelling ahead or to an obstacle located in front of the vehicle by a warning or by a braking intervention in order to prevent a collision with the motor vehicle or obstacle ahead.
German Offenlegungsschrift No. 196 47 283 discloses an arrangement for avoiding and/or minimizing collisions in road traffic which has sensors for sensing individual parts of the surroundings of a motor vehicle supplied with the arrangement. These individual items of information relating to the surroundings can, in the simplest case, be output signals of sensors for detecting, for one or more obstacles, at least the distance and the relative speed between the motor vehicle and the obstacle which has been detected, and its size, in order to classify the obstacles.
In addition, the sensors for sensing individual parts of the surroundings of the vehicle may advantageously also include devices for determining the course of the road, for example, the radii of bends in he road, the prevailing visibility and the condition of the road surface or, for example, detectors for detecting road signs and/or notice signs and/or traffic lights.
From this collection of information relating to individual parts, a representation or model of the surroundings of the vehicle is produced and supplied to an evaluation unit for evaluating the representation and/or the parts of the representation. In addition, the operating characteristics of the motor vehicle are sensed by further sensors, for example sensors which sense the travel direction and the longitudinal and transverse movements or speeds of the vehicle. The output signals from these sensors are transmitted to an evaluation unit for evaluating the instantaneous vehicle driving characteristics.
Both the output signals from the evaluation unit for evaluating the representation and/or parts of this representation and the output signals from the evaluation unit for evaluating the operating characteristics of the motor vehicle are supplied to a processing device which determines from these output signals a physical parameter limit for the avoidance of a collision situation. If this physical parameter limit is reached or exceeded, downstream control devices generate control signals for influencing the driving functions of the motor vehicle, at least a braking/acceleration device and/or a steering device for the motor vehicle, depending on the output signals from the evaluation unit for evaluation of the representation of the surroundings and of the evaluation unit for evaluating the operating characteristics of the motor vehicle, i.e. the devices which influence the driving functions of the motor vehicle are acted on directly.
After the driving functions of the vehicle have been taken over by the vehicle control device, its function is to defuse the imminent collision situation, i.e. to avoid an accident. In individual cases, this will not always be possible. Consequently, the unit for generating control signals for the active driving functions will also transmit control signals for activating the passive safety systems, for example airbags, a hazard flashing light system or an emergency call device.
In cases in which a danger has been detected in good time, but, under certain circumstances, a collision situation is unavoidable, the arrangement carries out a measure for limiting damage by, for example, preferring a collision with a rubbish bin on the sidewalk to a collision with a person on the road.